DE 199 04 721 A1 refers to an electromechanically actuated vehicle braking system which has electrical braking control circuits, namely one for the brakes on the front axle and one for the brakes on the rear axle. The two control circuits each have their own power supply and their own electronic control unit, which are electrically connected to a brake pedal. The two control units operate independently of one another but can communicate with one another and can thereby detect faults in a control unit. A fault is then deemed to be present when the two control units determine different control signals from the same sensor input signals. In the event of a fault, the two control units are deactivated and the brakes are then controlled by decentralized control units which are assigned to the individual wheels and can perform only simple basic functions.
Modern utility vehicle braking systems have a dual-circuit pneumatic control system and an electronic braking control system, thus making it possible to transmit signals in a more rapid manner and improving the response behavior of the braking system. The costs of electromechanical control components are also frequently lower than the costs of pneumatic control components. Another advantage is the lower outlay on installation. Electropneumatic braking systems, in particular, in which the braking force is applied using compressed air but braking is controlled electronically are customary nowadays. A fundamental “quality criterion” of electrical or electronic braking control systems is their reliability or fail-safety.
DE 199 15 253 A1 refers to a braking system for vehicles, said braking system having two brake circuits and containing, in a central unit, two microcomputers which are each supplied with power from separate power sources. The two microcomputers activate a plurality of brake actuating devices for individual wheel brakes using two separate redundant bus systems. This activation is always effected in a parallel manner using the two bus systems. Measuring devices which are coupled to a brake pedal are provided in order to activate the two microcomputers.
DE 35 02 049 A refers to a brake pressure control device for a motor vehicle having a foot brake valve which transmits signals to an electronic control unit which, for its part, activates pressure-regulating valves for wheel brakes.
WO 01/62569 A refers to an electronic braking control system having three power sources for the power supply. The power sources are decoupled from one another by diodes.
DE 196 40 148 A refers to an electronic braking system having a plurality of vehicle modules which communicate via a data bus. Individual modules are DC-isolated from one another by optocouplers.
DE 195 09 150 A refers to a vehicle braking system having at least two brake circuits, said braking system respectively having a control unit which is controlled microprocessors which are independent of one another. A monitoring computer monitors the two other control units.
DE 32 04 185 A refers to a pressure-medium braking system having a foot brake valve which electrically activates braking control valves.